The present invention relates to an alumina-zirconia sintered body, a process for production thereof, and an impact grinder using said alumina-zirconia sintered body.
Alumina-zirconia type sintered bodies are known to have a high strength, a high toughness and a high abrasion resistance. U.S. Pat. No. 4,316,964, JP-B 59-24751, JP-B 61-59265, etc. disclose that an alumina-zirconia sintered body can be made into a high-strength high-toughness sintered body by converting the zirconium oxide (hereinafter, referred to as ZrO.sub.2) present in the sintered body into a tetragonal crystal.
Even such a type of sintered bodies, however, cannot exhibit a sufficiently high abrasion resistance when the sintered body is put to use under severe abrasive conditions and particularly to uses in which particles collide with a great impact force.
Thus, as a method for improving abrasion resistance, methods for controlling the growth of particles by the use of a sintering assistant have been proposed. For example, JP-A 64-65067 has disclosed a method of using feldspar and kaolinite in combination as a sintering assistant. However, this method is disadvantageous in that feldspar involves alkali metal or alkaline earth metal which affects the stability of ZrO.sub.2, so that a sintered body of high abrasion resistance can be obtained by carrying out the calcining carefully.